How-To

Growing Potatoes

An ancient vegetable, potatoes were first cultivated by the ancient Incas in Peru. This crop came to America in 1621, and today is the most popular vegetable in the United States. If you love potatoes and have never tasted a homegrown one, you definitely need to try growing potatoes. Potatoes are cool-season vegetables and yield the best quality and number of tubers in the northern portion of the country. And just so you know: A potato isn’t a root but an underground storage stem called a tuber.

Some gardeners grow their potatoes in straw, placing straw around the 8-inch-tall stems instead of soil. This method yields potatoes that you don’t have to dig, but simply fish out of the straw. If you use the straw method, be sure to keep your straw layer consistent throughout the growing season. It will most likely break down and need to be topped off during the course of growing the potatoes.

Maximum tuber formation occurs when soil temperature is 60 F to 70 F. Tuber formation stops when soil temperature hits 80 F. Mulching soil with straw or other organic matter can help reduce soil temperature. Research has shown that maintaining a 6-inch-thick straw layer around potatoes keeps soil temperatures 10 degrees lower. Potatoes are sensitive to drought. Keep plants consistently moist, especially when plants flower and right after, since this is the peak time when tubers are forming.

Move potatoes to a different place in the garden each year to help limit disease and insect problems. For best success, rotate potatoes on a 3-year program, growing them in a different spot for three years in a row before cycling through the growing spots again.

Troubleshooting

Potatoes will develop areas of green skin when they’re exposed to direct sunlight during growth. The green areas have a bitter taste because the flesh contains a moderately poisonous compound. When preparing potatoes, cut away any green areas and discard. Potatoes in storage will develop green spots if they’re exposed to sunlight or fluorescent light. Keep stored potatoes in darkness. If your storage space isn’t completely dark, store potatoes in a box with a lid. Mounding soil or straw around potato stems will protect developing tubers during the growing season. Wedge-shaped leafhoppers feed on potato leaves, causing them to curl or crinkle and edges to turn brown. Flea beetles, which are tiny (1/16 inch), black, and shiny, create white streaks in leaves or small holes. They typically infest plants in late spring. If the infestation is bad enough, it can cause some leaves to die, which will reduce yield. Colorado potato beetles can also ravage plants. Read more about all of these pests and their control in our Pest Identification section.

Harvest and Storage

You can harvest new potatoes usually about two to three weeks after plants flower. If soil is loose enough, dig potatoes free with your hands. Otherwise, use a shovel or digging or spading fork to loosen soil near stems.Harvest all potatoes after vines have died. If the growing season has been rainy, wait a few days for soil to dry. It’s easier to dig potatoes in dry soil. You’ll find tubers 4 to 6 inches below the soil surface. Use a shovel or digging or spading fork, inserting the tool 6 to 10 inches away from the plant stem. Loosen and pry up soil gently, looking and feeling around for tubers.

Brush dry soil from potatoes. Don’t wash them if you plan to store them. Newly dug potatoes don’t have a tough skin. Handle tubers gently to avoid damaging and bruising them. Curing produces a tougher skin. To cure potatoes, place in a humid spot at roughly 55 F for two weeks.

If you plan to store potatoes into winter, select tubers that are firm and without soft spots. Store in a dark room with high humidity; the temperature should be 38 F to 40 F. Do not store potatoes with apples. Check potatoes frequently for sprout formation; knock off sprouts with your hands and dispose. Do not refrigerate potatoes. Tubers will hold at room temperature for 1 to 2 weeks.

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Shapes and sizes of homegrown potatoes will vary even from the same plant.

Rather than hilling these potato plants with soil, gardeners at the Wishard Slow Food Garden in Indianapolis layered straw around the plant stems.

It’s best to dig potatoes when the soil is dry.

This potato plant is flowering, which indicates that the tubers are forming underground. Keep plants well watered during and after flowering.